Hi Tuned, it occurs to me that maybe the question you should be asking is "what scale should I model in?" Of course product research is good and will help with a decision but with your permission I'd like to offer some suggestions, and discuss the relative merits of HO and N as I see it.
The advantage to N scale is that it's much smaller, allowing for "larger" layouts in the same space. This means more track, more industries, and longer, more prototypical trains. If you like big spaces, big rosters with lots of engines and rolling stock, N provides it.
The drawback to N scale is that it's that much smaller. This means smaller parts that are harder to see and harder to work with, less detail, no on-board sound. It also means you'll need more engines and rolling stock, more industries, more turnouts, etc. That can get expensive fast.
The advantage to HO is that it's bigger. More detail (including building interiors etc), onboard sound, and easier to work with. Also, there are more products available in HO, although N is gaining ground.
The disadvantage to HO is that it's bigger - you get the idea - less room for track, compression a necessity, shorter trains, etc.
I made the choice to model in HO mainly because I like buildings and factories as much as I like trains and operations - maybe more. There are times, during track planning, that I wish I'd gotten into N because of space limitations, but basically this is the choice that works best for me. Also, my eyesight is not getting any better, and I find HO detail parts and kits are still pretty eensy beensy!!
The best approach is to determine where your main interest lies. Is it prototypical operations? Switching? Running long unit trains? Super detailing?
If you're new to the hobby you may not have decided this yet. In that case, you could start by building a small diorama - one that contains some tracks and a building or 2 so you can practice track laying, ballasting etc. Since you have an N locomotive already, why not start with a small N scale diorama? If you like working in that scale, stick with it. If you find it too difficult, try one in HO.
In any case, welcome to an awesome hobby, and welcome to the Gauge!!!!
Val